Ariel Castro brothers 'unaware' of kidnappings

Chicago: The brothers of the US man charged with kidnapping and raping three women, locking them in his home for a decade, say they had no idea what was happening.

"If I knew that my brother was doing this, I would not be, not - in a minute, I would call the cops because that ain't right," Pedro Castro, 54, told CNN.

"If I knew, I would have reported it, brother or no brother," he added.

Pedro and his youngest brother, 50-year-old Onil, were arrested soon after their brother Ariel Castro on Monday, when the three women, and a daughter born to one of them while in captivity, were discovered at Ariel's home in Cleveland, Ohio.

The two, and their 71-year-old mother, are in hiding, saying people have thrown rocks at their homes and sent them death threats over the internet, CNN reported.

Ariel Castro, a 52-year-old unemployed bus driver, was arrested after one of the victims, 27-year-old Amanda Berry, managed to call out to a neighbour, who kicked in the door to the suspect's home and rescued her and her six-year-old daughter.

Berry offered similar words, while Knight said she was "healthy, happy and safe and will reach out to family, friends and supporters in good time."

But Wooley said, despite "numerous requests" for interviews, the three women would stay silent for now.

"First, there is a pending criminal investigation and prosecution," he said, adding the three women were "victims and witnesses".

"It is not in the best interests of anyone connected with that proceeding for Ms Berry, Ms DeJesus, and Ms Knight to be making statements to the media while that proceeding is pending."

And he added, "Second, and most importantly, Ms Berry, Ms DeJesus, and Ms Knight have asked - in fact, have pleaded - for privacy at this time so that they can continue to heal and reconnect with their families.

The prosecutor has said investigators would go back over the many torments Castro allegedly inflicted on the women during their long ordeal, with the aim of bringing additional charges, including ones that may carry the death penalty.

Castro was ordered held on an $US8 million ($A7.96 million) bond on Thursday.